I know what you say. I use this other “trick” and it works better: to your “Unknow” i add an UTF8 smiley, like or
which is not “modifiable” in no way (no genre, no singular/plural, etc…). And it let me detect this kind of scenarios to improve the answer to user with extra-tips not provided by the IA
Note: Actually, I take this idea from Bing Chat, when I saw that they used emojis! Until that moment it had not occurred to me that this was possible.